Conventional tractor trailer vehicles have a trailer body of height greater than the height of the tractor which tows the trailer. Furthermore, the front wall of the trailer body is spaced rearwardly from the rear wall of the tractor cab to permit the tractor to turn relative to the trailer.
Prior U.S. Pat. Nos. such as Madzsar et al 3,711,146; Cook et al 3,834,752; Servais et al 3,945,677; and Keedy 4,142,755 disclose various devices for streamlining tractor trailer vehicles by filling in the gap between the tractor and the trailer through the use of inflated flexible bags or a plurality of hinged or telescoping metal panels. Other prior U.S. Pat. Nos. such as Taylor et al 4,156,543 and Wiley 4,257,640 disclose the use of a tractor roof mounted deflector used in conjunction with a retractible or articulated baffle which extends between the cab and the front wall of the trailer.
Although aerodynamically efficient, such drag reducers have not been commercially successful because of the cost, complexity, and problems of maintenance and serviceability. In some systems, both the tractor and trailer must carry cooperating elements of the system so that both the tractor and the trailer must be dedicated for use with correspondingly equipped tractors and trailers. Furthermore, such systems complicate the task of hooking and unhooking the tractor from the trailer.
It would be desirable to provide a commercially practical aerodynamic drag reducer which aerodynamically approximates the effect of completely filling the gap between the tractor and trailer and yet has no connection to the trailer to thereby facilitate interchangeability between tractors and trailers.